In general, a coated abrasive can be defined as a plurality of abrasive grains bonded to a backing by means of one or more binders. The backing can be rigid like a metal plate or the backing can be flexible like cloth, paper, film, non-wovens or vulcanized fiber. The majority of the coated abrasive backings used in industry today are flexible. The binders can be inorganic materials such as metals or silicates or organic materials such as phenolic resins, ureaformaldehyde resins, epoxy resins or glue. Typical examples of abrasive grains are diamond, cubic boron nitride, fused alumina, ceramic aluminum oxide, silicon carbide, boron carbide, silicon nitride, etc. In the abrasive industry, diamond and cubic boron nitride (CBN) are considered "superabrasives" because their abrasive qualities are vastly superior to the other known abrasive grains. However, these superabrasive grains are also considerably more expensive. In most applications, if a superabrasive grain is employed, a metal binder is used in order to obtain the optimum abrading performance. The other binders listed above typically do not have the strength and integrity necessary to take full advantage of the unique abrading properties associated with superabrasives. Examples of coated abrasives which contain metal bonded superabrasives include: U.S. Pat. Nos. 3,860,400; 4,047,902; 4,078,906; 4,256,467; 4,288,233; 4,826,508 and 4,874,478; British Application 2,200,920 and World Patent Office 90/00105.
It is also known in the art to laminate the coated abrasive to another substrate. For example, British Application 2,164,053 teaches a coated abrasive comprising diamond abrasive grains bonded to a flexible backing by means of an electroplated metal binder. This coated abrasive is then in turn laminated to another substrate by means of an organic laminating adhesive which is heat resistant, solvent resistant and water resistant. However, in certain severe abrading applications, organic laminating adhesives do not exhibit the necessary strength and integrity. Consequently, the laminating adhesive will fail first before the diamond grains fail and the full utilization of the diamond abrasive grain is not achieved.
In some instances, it may be desired to laminate the coated abrasive to a more rigid substrate. U.S. Pat. No. 2,820,746 and British Patent 760,526 disclose a coated abrasive comprising a metal backing with abrasive grains bonded to the backing by means of a metal binder. The coated abrasive is then laminated to a more rigid substrate by the use of a metallic adhesive. However, coated abrasives having metal backings generally are not sufficiently flexible to conform to substrates of varying shapes.
What industry needs today are coated abrasive articles containing flexible backings which are bonded to another substrate by means of a metal adhesive and processes for producing such articles. Such abrasive articles may have substantially any desired shape.